Robert Work, US Deputy Secretary of Defense, at a christening ceremony for the autonomous ship ''Sea Hunter'', developed by DARPA, in Portland, Oregon before its christening ceremony on April 7, 2016.

PHOTO: Reuters

The US military is dropping "cyber bombs" on Islamic State for the first time as part of a stepped-up coordinated effort that has put increasing pressure on the militant group, Deputy Defence Secretary Robert Work said on Tuesday.

"Those guys are under enormous pressure. Every time we have gone after one of their defended positions over the last six months, we have defeated them. They have left, they have retreated," Work told reporters on a military plane en route to a Colorado air base.

He said US and coalition forces were putting pressure on Islamic State from all directions, using every possible military capability, including cyber attacks, to defeat the group.